cell-mediated immunity

(noun)

Adaptive immunity that is not controlled by antibodies and is instead mediated directly by immune cells themselves, most notably type 1 helper T cells and cytotoxic T-cells.

Related Terms

Examples of cell-mediated immunity in the following topics:

  • Types of Adaptive Immunity

    • The adaptive immune response is mediated by B and T cells and creates immunity memory.
    • There are two subdivisions of the adaptive immune system: cell-mediated immunity and humoral immunity.
    • Cell mediated immunity is controlled by type 1 helper T cells (Th1) and cytotoxic T cells.
    • Humoral immunity refers to the component of the adaptive immune response that is caused by B cells, antibodies, and type 2 helper T cells (Th2), as well as circulating mast cells and eosinophils to a lesser extent.
    • This binding will cause degranulation and release of inflammatory mediators that start an immune response against the antigen.

  • Lymphoid Cells

    • A lymphocyte is a type of white blood cell in the immune system.
    • T and B lymphocytes are the main forces of adaptive immunity, which includes cell-mediated and humoral immunity.
    • T cells are involved in cell-mediated immunity whereas B cells are primarily responsible for humoral immunity.
    • There are two types of T cells involved in adaptive, cell-mediated immunity.
    • Cytoxic T cells cause much of the damage associated with cell-mediated hypersensitivity, autoimmune disorders, and organ transplant rejection.

  • Specific T-Cell Roles

    • The different categories of T cells are the basis for cell-mediated immune system activity.
    • Cytotoxic T cells recognize their antigen on pathogens through their T cell receptor, and will kill the pathogen through degranulation and cell-mediated apoptosis.
    • The secondary immune response mediated by memory T cells is much faster and more effective at eliminating pathogens compared to the initial immune response.
    • Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus.
    • Natural killer T cells (NKT cells – not to be confused with natural killer cells) bridge the adaptive immune system with the innate immune system.

  • Lymphocytes

    • A lymphocyte is a type of white blood cell in the vertebrate immune system.
    • A lymphocyte is a type of white blood cell in the immune system, including both the B and T cells of the adaptive immune system and natural killer (NK) cells of the innate immune system .
    • B and T cells and their various subdivisions perform many adaptive immune functions.
    • T cells are a major component in cell-mediated adaptive immunity because they provide a pathway for the direct killing of pathogens.
    • They have an immunosuppressive effect that inhibits cell-mediated immunity at the end of a response and destroys autoimmune T cells that aren't filtered out by negative selection in the thymus.

  • WBC Function

    • Leukocytes (white blood cells) provide a number of functions that are primarily related to the immune system goal of defending the body from pathogens (foreign invaders).
    • Innate immune system functions from leukocytes include:
    • Adaptive immune functions of leukocytes include:
    • The T cells will then start the adaptive immune response by rapidly proliferating and differentiating.
    • Cell mediated activities.

  • Natural Killer Cells

    • Natural killer (NK) cells are cytotoxic lymphocytes critical for the innate immune system.
    • Natural killer (NK) cells are cytotoxic lymphocytes critical to the innate immune system.
    • The role of NK cells is similar to that of cytotoxic T cells in the adaptive immune response.
    • NK cells use wo cytolytic granule-mediated apoptosis to destroy abnormal and infected cells.
    • Describe the role of natural killer cells in the innate immune system

  • Hypersensitivity

    • Mediators: IgE and IgG4.
    • Cytotoxic Hypersensitivity (Type II) is an immune response to human cells with foreign antigens.
    • Mediators: IgG (complement).
    • Associated disorders: Contact dermatitis, Mantoux test, Chronic transplant rejection, Multiple sclerosis, T-cells VAutoimmune disease receptor mediated, Graves' disease,Myasthenia Gravis.
    • Mediators: IgM or IgG (complement).

  • Overview of Adaptive Immunity

    • The adaptive immune system is composed of highly-specialized systemic cells and processes that eliminate or prevent pathogenic growth.
    • The adaptive immune system, also known as the specific immune system, is composed of highly-specialized systemic cells and processes that eliminate or prevent pathogenic growth.
    • Active immunity is generally long-term and can be acquired by infection followed by B cells and T cells activation, or artificially acquired by vaccines in a process called immunization.
    • In these cases, memory cells form for an antigen that elicits an immune response without actually being caused by a pathogen, which leads to immune system mediated-damage to the body from mast cell, antibody, or T-cell mediated activities and inflammation.
    • Helper T cells, or Th cells, coordinate immune responses by communicating with other cells.

  • Active and Passive Humoral Immunity

    • The humoral immune response is the aspect of immunity that is mediated by secreted antibodies.
    • The humoral immune response (HIR) is the aspect of immunity that is mediated by secreted antibodies produced by B cells.
    • Natural active immunity generally occurs as a result of infection with a pathogen, in which memory cells that remember the antigen of the infectious agent remain in the body.
    • Unlike active immunity, passive immunity is short lived (often only for a few month), because it does not involve the production and upkeep of memory cells.
    • Maternal passive immunity is a type of naturally acquired passive immunity, and refers to antibody-mediated immunity conveyed to a fetus by its mother during pregnancy.

  • Types of Cytokines Participating in Immune Response

    • Some of the more important ones include inflammatory mediators such as IL-1, IL-4, and IL-6, the potent anti-inflammatory IL-10, and other interleukins involved with T and B cell signaling following antigen presentation.
    • Many interleukins are also considered lymphokines, interleukins released by helper T cells to organize immune responses.
    • Chemokines are protein cytokines that are mainly involved in facilitating chemotaxis (chemical-stimulated movement) in immune cells.
    • By definition, inflammatory mediators in other classes of cytokines are also considered chemokines.
    • It is a protein released by NK cells, macrophages, and helper T cells, typically in systemic immune responses.